One such shapeable articulated structure has been described in the European patent publication No. 0062448 A1 (EPC Appl'n. No. 8231533.4). In that document, each described structure comprises an array of inter-connected first and second elements, the elements of one such kind being provided with clamping means for engaging and clamping parts of at least two adjoining elements of the other kind, and the said array being rendered rigid by tightening the respective clamping means. It has been found in practice that articulated structures as described in that publication have certain disadvantages which it is desirable to obviate; thus, it is desirable to provide a lighter, stronger, more flexible articulated structure that is more versatile in its fields of application, that is more simply secured in a seat frame, and that is more resiliently flexible in use.